Crystalline Phase Transitions and Reactivity of Ammonium Nitrate in Systems Containing Selected Carbonate Salts

Maciej Kaniewski,Marcin Biegun,Marta Huculak-Mączka,Józef Hoffmann,Jakub Zieliński,Krystyna Hoffmann

doi:10.3390/cryst11101250

Maciej Kaniewski, Marcin Biegun + Show 4 more

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https://doi.org/10.3390/cryst11101250

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Abstract

Samples of pure ammonium nitrate (AN) and its mixtures with calcium carbonate, potassium hydrogen carbonate and potassium carbonate were investigated with the use of differential thermal analysis with mass spectrometry, powder X-ray diffraction and scanning electron microscopy. The main objective of the study was to determine the influence of selected carbonate materials on phase transitions of ammonium nitrate and to consider a possibility to use such potassium salts as fillers in fertilizer production. It was proven that all carbonate salts caused the absence of a phase transition that normally would occur at around 84–86 °C. Potassium carbonates were too reactive in systems containing AN. Based on the performed study, it was concluded that even though potassium carbonates are not fit to replace mineral fillers in the production process of fertilizers containing ammonium nitrate, they could be used in lesser amounts to remove the presence of low-temperature phase transitions of AN.

Highlights

Ammonium nitrate (AN) is an inorganic salt that contains 35 wt % N in the form of ammonium and nitrate ions
Performed analyses of mixtures containing ammonium nitrate and one of either calcium carbonate, potassium carbonate or potassium hydrogen carbonate allowed us to obtain a deeper understanding of studied systems
It was proven that phase transitions of ammonium nitrate were heavily influenced by the presence of any chosen additive and that carbonate salts of potassium reacted with ammonium nitrate at room temperature

Summary

Introduction

Ammonium nitrate (AN) is an inorganic salt that contains 35 wt % N in the form of ammonium and nitrate ions It is highly hygroscopic and dissolves in water, absorbing heat from the environment in the process. It does not form hydrates and is characterized by good solubility in alcohols, such as methanol and ethanol, along with acetone and some organic and inorganic acids, such as nitric and formic acid [1,2]. AN is a chemical of a great practical importance due to its high nitrogen content. It is widely used in agriculture and horticulture as a mineral fertilizer. It has a few unfavorable properties, the most important of which are its tendency to cake, mainly caused by a high hygroscopicity of the salt and an absorption of moisture from the air, and a possibility to explosively decompose, which is a real threat that was proven by numerous, welldocumented accidents that have occurred in the past, the most recent being the explosions in Beirut, Lebanon [3,4,5,6,7,8]

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